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The National Institute of General Medical Sciences (NIGMS),
one of the National Institutes of Health, supports all research
featured in this digest. Although only the lead scientists
are named, coworkers and other collaborators also contributed
to the findings. To read additional news items, visit NIGMS
News.

Cool Image: The Cellular Metropolis

Like a major city, a cell teems with specialized workers
that carry out its daily operations—making energy, moving
proteins, or helping with other tasks. Researchers took microscopic
pictures of thin layers of a cell and then combined them to
make this 3-D image featuring color-coded organelles—the
cell’s “workers.” Using this image, scientists
can understand how these specialized components fit together
in the cell's packed inner world. Courtesy of Kathryn Howell,
a cell biologist at the University of Colorado Health Sciences
Center.

FDA Approves HIV Drug for Resistant Infections

The U.S. Food and Drug Administration has approved Prezista (darunavir), the first antiviral drug designed to treat drug-resistant strains of HIV. The drug is a molecule designed by Arun Ghosh, a synthetic organic chemist now at Purdue University. Ghosh created the molecule based on the structure of HIV protease, an enzyme that enables the virus to reproduce and the target of many existing therapies. Ghosh's molecule blocks the enzyme's activity by binding to its backbone. This region is less likely to change as the virus evolves, reducing the likelihood that the virus will become resistant to the new drug. The drug enhances the current approach for treating HIV infection and may be available to patients this year.

High Weight Doesn’t Always Equal High
Fat

What’s the skinny on fat? Size matters. A team of researchers
led by statistical geneticist Gary Churchill of the Jackson
Laboratory studied the genetic networks that influence body
size and body fat in mice. The scientists found that the two
networks can act independently, suggesting that a high weight
doesn’t necessarily equal a high percentage of body
fat. If the findings hold up in humans, they may point to
the value of calculating obesity not just by weight and height,
but also by body size. Churchill leads the Jackson Center
for Genome Dynamics, a new NIGMS-supported systems biology
center that uses experimental and computational approaches
to understand how our genes interact to keep us healthy or
make us sick.

Spider Venom Opens Door to New Drugs

Caption:
Brown recluse spider. Courtesy of John S. Williams.

Ion channels are like carefully controlled doors into cells.
By selectively allowing charged molecules called ions to
pass, the channels generate electrical signals key to neuronal
and muscular function. Some channels require a special molecular
key to open, while others respond to electrical jolts. With
an enzyme from the venom of the brown recluse spider, physiologist
Zhe Lu of the University of Pennsylvania forced open a type
of ion channel previously known only to respond to an electrical
trigger. Because ion channels are involved in a host of
biological processes, the work may pave the way for new
drugs that target the channels.

Metabolic Enzyme Moonlights in Gene Expression

Most enzymes involved in energy metabolism stick to the job
of breaking down complex molecules into smaller molecular
building blocks and energy. Not so for one cog in this intricate
process. A study led by molecular biologist Jef Boeke of Johns
Hopkins University revealed that the enzyme Acs2p also plays
a key role in gene regulation—loss of Acs2p leads yeast
cells to turn off 70 percent of their genes and die. According
to the study, this sweeping effect on gene activity results
from the accompanying loss of Acs2p’s product, acetyl-CoA,
which is involved in a global gene activation process known
as histone acetylation. These findings could lead to new ways
to slow cellular aging, which has been linked to energy metabolism
and histone acetylation in yeast and other organisms.

Biomedical Beat is produced by the Office of Communications and Public Liaison
of the National Institute
of General Medical Sciences. Some of the research briefs
in this digest were generated from university or national
laboratory news releases. For more information about Biomedical
Beat, please contact the editor, Emily Carlson, at carlsone@nigms.nih.gov
or 301-594-1515. To talk to someone at NIGMS about this research,
call 301-496-7301. The material in this newsletter is not
copyrighted and we encourage its use or reprinting.